1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus and, more particularly, to a semiconductor manufacturing apparatus for printing a semiconductor device circuit or a device pattern on a semiconductor wafer and to a method of using measuring functions of the manufacturing apparatus to improve maintenance of the apparatus.
2. Description of the Related Art
A semiconductor exposure apparatus, e.g., a stepper used in the process of manufacturing a semiconductor device is an apparatus in which a reduced image of a fine pattern formed on a reticle (or mask) is projected onto a wafer, and in which a plurality of shot areas on the wafer are successively positioned to be exposed to the projected pattern. Currently, there are two types of steppers used: a step-and-repeat type in which the entirety of a shot area of a wafer is exposed at one time, each time the wafer is moved one step, and a step-and-scan type in which a shot area of a wafer is exposed in a scanning manner each time the wafer is moved one step.
In such semiconductor exposure apparatuses, there is a need to correct printing errors due to changes in the apparatus over time and/or printing errors caused by the particular wafer treatment process. It is thought that errors due to (1) the apparatus are those caused by changes over time in the shapes of the structural members of the apparatus and by deterioration over time of either moving parts of the apparatus or a projection lens that is used to project reticle patterns onto a wafer, and (2) the particular wafer treatment process are those caused by warp, expansion or contraction of a wafer due to wafer heat treatment or the like and by irregularities in the wafer surface due to etching, doping, deposition or the like in the wafer treatment process.
Printing errors resulting from such causes appear as various errors, such as an XY-shift error of a printed pattern with respect to a shot area on a semiconductor wafer, a misalignment of patterns printed on a semiconductor wafer, a magnification error of an array of printed patterns with respect to an array of shot areas through a wafer (wafer magnification error), a magnification error in patterns in one shot (shot magnification error), a focus error, and so on.
In the above-mentioned semiconductor exposure apparatuses, changes over time of the apparatus and changes caused by the particular wafer treatment process are related to the errors. Therefore, to prevent such errors, correction values with respect to causes related to each error are managed as offset values. For example, with respect to an XY-shift error, an alignment offset value for correcting a cause of a change over time of the apparatus and an XY-shift offset value for correcting a change caused by the particular wafer treatment process are prepared.
Methods of measuring such offset values by using various measuring functions of a semiconductor exposure apparatus are known. Conventionally, however, an operator executes measurements for maintenance of an apparatus by using measuring functions of the apparatus and performs correction value measurements and actual correction as occasion arises.
Conventionally, when operations for maintenance of an apparatus are performed, an operator selects maintenance commands according to maintenance items and executes operations by the maintenance commands. Therefore, when a periodical maintenance process or the like is executed by a plurality of maintenance commands, there is a possibility of omitting execution of some of the maintenance commands or occurrence of an operation execution order error such that the overall maintenance process, including measurement of offset values, cannot be correctly executed.